Photocurable composition for imprint, method for producing film using the same, method for producing optical component using the same, method for producing circuit board using the same, and method for producing electronic component using the same

ABSTRACT

A photocurable composition for imprint at least has a polymerizable compound (A) and a photopolymerization initiator (B), in which the polymerizable compound (A) contains 20% by weight or more of a multifunctional (meth)acrylic monomer and the glass transition temperature of a photocured substance of the photocurable composition is 90° C. or more.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.15/537,320, filed Jun. 16, 2017, which is a National Stage filing ofInternational Application No. PCT/JP2015/006244 filed Dec. 15, 2015,which claims the benefit of Japanese Patent Application Nos.2014-257798, filed Dec. 19, 2014, 2015-099486, filed May 14, 2015, and2015-232535, filed Nov. 28, 2015 which are hereby incorporated byreference herein in their entirety.

TECHNICAL FIELD

The present invention relates to a photocurable composition for imprint,a method for producing a film using the same, a method for producing anoptical component using the same, a method for producing a circuit boardusing the same, and a method for producing an electronic component usingthe same.

BACKGROUND ART

A demand for miniaturization in semiconductor devices, MEMS, and thelike has increased. Therefore, a micromachining technique utilizing apattern of a resist (photocurable composition for nanoimprint) which isformed on a substrate (wafer) and has a predetermined shape as a moldhas recently drawn attention in addition to a former photolithographictechnique. This technique is also referred to as an optical imprint(optical nanoimprint) and can form a fine structure of the order ofseveral nanometers on a substrate (PTL 1). According to the opticalimprint technique, a resist is first applied to a pattern formationregion on a substrate (Arrangement step). Next, this resist is moldedusing a mold on which a pattern is formed (Mold contact step). Then,light is emitted to cure the resist (Light irradiation step), and thenthe cured resist is released (Mold release step). By carrying out thesesteps, the pattern of the resist cured substance (photocured film)having a predetermined shape is formed on the substrate. Furthermore, byrepeating all the steps described above at other positions on thesubstrate, a fine structure can be formed on the entire substrate.

The photocured film having the pattern formed on the substrate by theoptical imprint technique is sometimes utilized as a mask in processinga base substrate using a dry etching technique. In this case, in orderto process the base substrate with a good yield, the photocured film isrequired to have high dry etching resistance. Moreover, in manufacturinga semiconductor device, it is required to form a circuit pattern with anaccuracy of about ±10 to 12% of a desired line width.

CITATION LIST Patent Literature

PTL 1: Japanese Patent Laid-Open No. 2007-186570

SUMMARY OF INVENTION Technical Problem

When transferring the pattern of the resist cured substance to a circuitpattern using the dry etching technique, the resist cured substancethermally expands due to the reaction heat generated in etching.Therefore, when the coefficient of thermal expansion of the resist curedsubstance is large, expansion and distortion of the pattern line widthare caused, which has posed a problem that a circuit pattern with ademanded accuracy is not obtained.

Moreover, when industrially utilizing the optical imprint method, it hasbeen required in order to obtain high productivity that, after bringinga photocurable composition for imprint into contact with a mold, thephotocurable composition for imprint is promptly filled into concaveportions of a fine pattern on the mold.

In order to solve the above-described problems, a photocurablecomposition for imprint having small thermal expansion in curing andhaving excellent filling properties is required.

The present invention provides a photocurable composition for imprinthaving small thermal expansion in dry etching and having excellentfilling properties in an optical imprint method. The present inventionalso provides a film production method using a photocurable compositionfor imprint, a method for producing an optical component using the same,a method for producing a circuit board using the same, and a method forproducing an electronic component using the same.

Solution to Problem

The present invention is a photocurable composition for imprint at leasthaving a polymerizable compound (A) and a photopolymerization initiator(B), in which the polymerizable compound (A) contains 20% by weight ormore of a multifunctional (meth)acrylic monomer and the glass transitiontemperature of a photocured substance of the photocurable composition is90° C. or more.

Further features of the present invention will become apparent from thefollowing description of exemplary embodiments with reference to theattached drawings.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1A is a schematic cross sectional view illustrating an example of amethod for producing a film of this embodiment.

FIG. 1B includes FIGS. 1B(b-1) and 1B(b-2) illustrating schematic crosssectional views illustrating the example of a method for producing afilm of this embodiment.

FIG. 1C is a schematic cross sectional view illustrating the example ofa method for producing a film of this embodiment.

FIG. 1D includes FIGS. 1D(d-1) and 1D(d-2) illustrating schematic crosssectional views illustrating the example of a method for producing afilm of this embodiment.

FIG. 1E is a schematic cross sectional view illustrating the example ofa method for producing a film of this embodiment.

FIG. 1F is a schematic cross sectional view illustrating the example ofa method for producing a film of this embodiment.

FIG. 1G is a schematic cross sectional view illustrating the example ofa method for producing a film of this embodiment.

DESCRIPTION OF EMBODIMENTS

Hereinafter, an embodiment of the present invention is described indetail with reference to the drawings as appropriate. However, thepresent invention is not limited to the embodiments described below. Inthe present invention, those obtained by, for example, altering andmodifying as appropriate the embodiments described below withoutdeviating from the scope based on usual knowledges of the personsskilled in the art is included in the scope of the present invention.

Photocurable Composition for Imprint

In this embodiment, a photocurable composition for imprint is a curablecomposition at least containing a component (A) and a component (B)described below:

Component (A): polymerizable compound; andComponent (B): Photopolymerization initiator.

In particular, the photocurable composition for imprint is suitable forthe use of forming a nano-order (1 nm to several hundreds nm) pattern ofa photocured film on a base material, such as a semiconductor substrate,which is referred to as nanoimprint. Furthermore, the photocurablecomposition for imprint is also suitable for the use of dry etching aphotocured film formed by the nanoimprint to process the base material.

In this embodiment, the photocured film means a film obtained bypolymerizing the photocurable composition on a substrate, and thencuring the same. Furthermore, the photocured film may have a patternshape.

Hereinafter, each component is described in detail.

Component (A): Polymerizable Compound

The component (A) is a polymerizable compound. Herein, in thisembodiment, the polymerizable compound is a compound which reacts with apolymerization factor (radical and the like) generated from thephotopolymerization initiator (component (B)) to form a film containinga high molecular weight compound by a chain reaction (polymerizationreaction).

As such a polymerizable compound, a radical polymerizable compound ismentioned, for example. The polymerizable compound which is thecomponent (A) may contain one kind of a polymerizable compound or maycontain two or more kinds of polymerizable compounds.

The radical polymerizable compound is suitably a compound having one ormore acryloyl groups or methacryloyl groups, i.e., a (meth)acryliccompound.

Therefore, the component (A) (polymerizable compound) of thephotocurable composition for nanoimprint suitably contains a(meth)acrylic compound. The main component of the component (A) is moresuitably a (meth)acrylic compound. It is the most suitable for thecomponent (A) to contain only a (meth)acrylic compound. Herein, the factthat the main component of the component (A) is a (meth)acrylic compoundmeans that the component (A) contains 90% by weight or more of a(meth)acrylic compound.

When the radical polymerizable compound contains two or more kinds ofcompounds having one or more acryloyl groups or methacryloyl groups, theradical polymerizable compound suitably contains a monofunctional(meth)acrylic monomer and a multifunctional (meth)acrylic monomer. Thisis because, by combining a monofunctional (meth)acrylic monomer and amultifunctional (meth)acrylic monomer, a photocured film having strongmechanical strength is obtained. In this embodiment, the multifunctional(meth)acrylic monomer is suitably contained in a proportion of 25% byweight or more. Thus, it is considered that the crosslink density of thephotocured film increases and the thermal expansion in dry etching canbe made small.

Examples of monofunctional(meth)acrylic compounds having one acryloylgroup or methacryloyl group include, for example,phenoxyethyl(meth)acrylate, phenoxy-2-methylethyl(meth)acrylate,phenoxyethoxyethyl(meth)acrylate,3-phenoxy-2-hydroxypropyl(meth)acrylate,2-phenylphenoxyethyl(meth)acrylate, 4-phenylphenoxyethyl(meth)acrylate,3-(2-phenylphenyl)-2-hydroxypropyl(meth)acrylate, (meth)acrylate ofEO-modified p-cumylphenol, 2-bromophenoxyethyl(meth)acrylate,2,4-dibromophenoxyethyl(meth)acrylate,2,4,6-tribromophenoxyethyl(meth)acrylate, EO-modifiedphenoxy(meth)acrylate, PO-modified phenoxy(meth)acrylate,polyoxyethylene nonylphenyl ether(meth)acrylate,isobornyl(meth)acrylate, 1-adamantyl(meth)acrylate,2-methyl-2-adamantyl(meth)acrylate, 2-ethyl-2-adamantyl(meth)acrylate,bornyl(meth)acrylate, tricyclodecanyl(meth)acrylate,dicyclopentanyl(meth)acrylate, dicyclopentenyl(meth)acrylate,cyclohexyl(meth)acrylate, 4-butylcyclohexyl(meth)acrylate, acryloylmorpholine, 2-hydroxyethyl(meth)acrylate, 2-hydroxypropyl(meth)acrylate,2-hydroxybutyl(meth)acrylate, methyl(meth)acrylate, ethyl(meth)acrylate,propyl(meth)acrylate, isopropyl(meth)acrylate, butyl(meth)acrylate,amyl(meth)acrylate, isobutyl(meth)acrylate, t-butyl(meth)acrylate,pentyl(meth)acrylate, isoamyl(meth)acrylate, hexyl(meth)acrylate,heptyl(meth)acrylate, octyl(meth)acrylate, isooctyl(meth)acrylate,2-ethylhexyl(meth)acrylate, nonyl(meth)acrylate, decyl(meth)acrylate,isodecyl(meth)acrylate, undecyl(meth)acrylate, dodecyl(meth)acrylate,lauryl(meth)acrylate, stearyl(meth)acrylate, isostearyl(meth)acrylate,benzyl(meth)acrylate, 1-naphthylmethyl(meth)acrylate,2-naphthylmethyl(meth)acrylate, tetrahydrofurfuryl(meth)acrylate,butoxyethyl(meth)acrylate, ethoxy diethylene glycol(meth)acrylate,polyethylene glycol mono(meth)acrylate, polypropylene glycolmono(meth)acrylate, methoxyethylene glycol(meth)acrylate,ethoxyethyl(meth)acrylate, methoxy polyethylene glycol(meth)acrylate,methoxy polypropylene glycol(meth)acrylate, diacetone(meth)acryl amide,isobutoxy methyl(meth)acryl amide, N,N-dimethyl(meth)acryl amide,t-octyl(meth)acryl amide, dimethylaminoethyl(meth)acrylate,diethylaminoethyl(meth)acrylate, 7-amino-3,7-dimethyloctyl(meth)acrylate, N,N-diethyl(meth)acryl amide,N,N-dimethylaminopropyl(meth)acrylamide, and the like but themonofunctional(meth)acrylic compounds having one acryloyl group ormethacryloyl group are not limited thereto.

Examples of commercially-available items of themonofunctional(meth)acrylic compound include Aronix M101, M102, M110,M111, M113, M117, M5700, TO-1317, M120, M150, and M156 (all manufacturedby Toagosei Co., Ltd.), MEDOL10, MIBDOLi0, CHDOLi0, MMDOL30, MEDOL30,MIBDOL30, CHDOL30, LA, IBXA, 2-MTA, HPA, Viscoat #150, #155, #158, #190,#192, #193, #220, #2000, #2100, and #2150 (all manufactured by OsakaOrganic Chemical Industry Co., Ltd.), Light acrylate BO-A, EC-A, DMP-A,THF-A, HOP-A, HOA-MPE, HOA-MPL, PO-A, P-200A, NP-4EA, NP-8EA, andEpoxyester M-600A (all manufactured by Kyoeisha Chemical Co., Ltd.),KAYARAD TC110S, R-564, and R-128H (all manufactured by Nippon KayakuCo., Ltd.), NK ester AMP-10G and AMP-20G (all manufactured byShin-Nakamura Chemical), FA-511A, 512A, and 513A (all manufactured byHitachi Chemical Co., Ltd.), PHE, CEA, PHE-2, PHE-4, BR-31, BR-31M, andBR-32 (all manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), VP(manufactured by BASF), ACMO, DMAA, and DMAPAA (all manufactured byKOHJIN Film & Chemicals Co., Ltd.), and the like but thecommercially-available items of the monofunctional(meth)acrylic compoundare not limited thereto.

Examples of multifunctional (meth)acrylic compounds having two or moreacryloyl groups or methacryloyl groups include, for example, trimethylolpropane di(meth)acrylate, trimethylol propane tri(meth)acrylate,EO-modified trimethylol propane tri(meth)acrylate, PO-modifiedtrimethylol propane tri(meth)acrylate, EO,PO-modified trimethylolpropane tri(meth)acrylate, dimethylol tricyclodecane di(meth)acrylate,pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate,ethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate,phenyl ethylene glycol di(meth)acrylate, 2-phenyl-1,3-propanedioldiacrylate, polyethylene glycol di(meth)acrylate, polypropylene glycoldi(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanedioldi(meth)acrylate, neopentyl glycol di(meth)acrylate, 1,9-nonanedioldi(meth)acrylate, 1,10-decanediol di(meth)acrylate, 1,3-adamantanedimethanol di(meth)acrylate, o-xylylene di(meth)acrylate, m-xylylenedi(meth)acrylate, p-xylylene di(meth)acrylate,tris(2-hydroxyethyl)isocyanurate tri(meth)acrylate,tris(acryloyloxy)isocyanurate, bis(hydroxymethyl)tricyclodecanedi(meth)acrylate, dipentaerythritol penta(meth)acrylate,dipentaerythritol hexa(meth)acrylate, EO-modified2,2-bis(4-((meth)acryloxy) phenyl)propane, PO-modified2,2-bis(4-((meth)acryloxy)phenyl)propane, EO,PO-modified2,2-bis(4-((meth)acryloxy)phenyl)propane, and the like are mentioned butthe multifunctional (meth)acrylic compounds having two or more acryloylgroups or methacryloyl groups are not limited thereto.

Examples of commercially-available items of the multifunctional(meth)acrylic compound include Yupimer UV SA1002 and SA2007 (allmanufactured by Mitsubishi Chemical Corporation), Viscoat #195, #230,#215, #260, #335HP, #295, #300, #360, #700, GPT, and 3PA (allmanufactured by Osaka Organic Chemical Industry Co., Ltd.), Lightacrylate 4EG-A, 9EG-A, NP-A, DCP-A, BP-4EA, BP-4PA, TMP-A, PE-3A, PE-4A,and DPE-6A (all manufactured by a Kyoeisha Chemical Co., Ltd.), KAYARADPET-30, TMPTA, R-604, DPHA, DPCA-20, -30, -60, -120, HX-620, D-310,andD-330 (all manufactured by NipponKayaku Co., Ltd.), Aronix M208,M210, M215, M220, M240, M305, M309, M310, M315, M325, and M400 (allmanufactured by Toagosei Co., Ltd.), Ripoxy VR-77, VR-60, and VR-90 (allmanufactured byShowa Denko), and the like are mentioned but thecommercially-available items are not limited thereto.

In the compound groups mentioned above, the (meth)acrylate refers toacrylate or methacrylate having an alcohol residue equivalent thereto.The (meth)acryloyl group refers to an acryloyl group or a methacryloylgroup having an alcohol residue equivalent thereto. The EO refers toethylene oxide. The EO-modified compound A refers to a compound in whicha (meth)acrylic acid residue and an alcohol residue of the compound Aare bonded to each other through the block structure of an ethyleneoxide group. The PO refers to propylene oxide. The PO-modified compoundB refers to a compound in which a (meth)acrylic acid residue and analcohol residue of the compound B are bonded to each other through theblock structure of a propylene oxide group.

Ohnishi Parameter of Component (A)

It is known that the dry etching speed V of a composition, the totalnumber of atoms N in a composition, the total number of carbon atoms NCin a composition, and the total number of oxygen atoms NO in acomposition have the following relationship shown in the followingexpression (1) (J. Electrochem. Soc., 130, p 143 (1983))

V _(OC) N/N _(C) −N _(O))  (1)

In Expression (1), N/(N_(C)−N_(O)) is commonly referred to as a “Ohnishiparameter”. For example, PTL 1 describes a technique of obtaining aphotocurable composition having high dry etching resistance by the useof a polymerizable compound component having a small Ohnishi parameter.

According to Expression (1) above, it is suggested that organiccompounds having a smaller number of oxygen atoms or having a largernumber of aromatic ring structures or alicyclic structures have smallerOhnishi parameters and have high dry etching resistance.

When the component (A) contains two or more kinds of polymerizablecompounds, the Ohnishi parameter is calculated using the followingexpression (2) as the mole fraction weighted average value.

OP=n ₁ OP ₁ +n ₂ OP ₂ + . . . +n _(n) OP _(n)  (2)

In this embodiment, the Ohnishi parameter of the component (A) issuitably 3.2 or less. When the component (A) is configured by apolymerizable compound in which the Ohnishi parameter is smaller than3.2, good dry etching resistance is obtained. On the other hand, whenthe component (A) is configured by a polymerizable compound in which theOhnishi parameter is larger than 3.2, the dry etching resistance is low,and therefore, a desired substrate processing accuracy cannot beobtained in some cases, which may lead to a reduction in yield.

Component (B): Photopolymerization Initiator

The component (B) is a photopolymerization initiator.

In this embodiment, the photopolymerization initiator is a compoundwhich detects light of a predetermined wavelength to cause generation ofthe polymerization factor (radical). Specifically, thephotopolymerization initiator is a polymerization initiator (radicalgenerating agent) which generates a radical by light (radiation rays,such as infrared rays, visible rays, ultraviolet rays, far ultravioletrays, X-rays, and charged particle beams, such as electron beams).

The component (B) may be configured from one kind of photopolymerizationinitiator or may be configured from two or more kinds ofphotopolymerization initiators.

Examples of the radical generating agents include, for example,2,4,5-triaryl imidazole dimers which may have substituents, such as a2-(o-chlorophenyl)-4,5-diphenyl imidazole dimer, a2-(o-chlorophenyl)-4,5-di(methoxyphenyl)imidazole dimer, a2-(o-fluorophenyl)-4,5-diphenyl imidazole dimer, and a 2-(o- orp-methoxyphenyl)-4,5-diphenyl imidazole dimer; Benzophenone derivatives,such as benzophenone, N,N′-tetramethyl-4,4′-diaminobenzophenone(Michler's Ketone), N,N′-tetraethyl-4,4′-diaminobenzophenone,4-methoxy-4′-dimethylaminobenzophenone, 4-chlorobenzophenone,4,4′-dimethoxy benzophenone, and 4,4′-diaminobenzophenone; α-aminoaromatic ketone derivatives, such as2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1,2-methyl-1-[4-(methylthio)phenyl]-2-morpholino-propane-1-on; quinones,such as 2-ethylanthraquinone, phenanthrene quinone, 2-t-butylanthraquinone, octamethyl anthraquinone, 1,2-benz anthraquinone,2,3-benz anthraquinone, 2-phenylanthraquinone, 2,3-diphenylanthraquinone, 1-chloroanthraquinone, 2-methyl anthraquinone,1,4-naphthoquinone, 9,10-phenanthraquinone, 2-methyl-1,4-naphthoquinone,and 2,3-dimethyl anthraquinone; benzoin ether derivatives, such asbenzoin methyl ether, benzoin ethyl ether, and benzoin phenyl ether;benzoin derivatives, such as benzoin, methyl benzoin, ethyl benzoin, andpropylbenzoin; benzyl derivatives, such as benzyl dimethyl ketal;acridine derivatives, such as 9-phenyl acridine and1,7-bis(9,9′-acridinyl)heptane; N-phenylglycine derivatives, such asN-phenylglycine; acetophenone derivatives, such as acetophenone,3-methyl acetophenone, acetophenone benzyl ketal, 1-hydroxy cyclohexylphenyl ketone, and 2,2-dimethoxy-2-phenyl acetophenone; thioxanthonederivatives, such as thioxanthone, diethyl thioxanthone, 2-isopropylthioxanthone, and 2-chlorothioxanthone; acyl phosphine oxidederivatives, such as 2,4,6-trimethyl benzoyl diphenyl phosphine oxide,bis(2,4,6-trimethyl benzoyl)phenyl phosphine oxide, andbis-(2,6-dimethoxy benzoyl)-2,4,4-trimethyl pentyl phosphine oxide;oxime ester derivatives, such as 1,2-octanedione,1-[4-(phenylthio)-,2-(O-benzoyloxime)], ethanone, 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazole-3-yl]-, and 1-(o-acetyl oxime); xanthone,fluorenone, benzaldehyde, fluorene, anthraquinone, triphenyl amine,carbazole, 1-(4-isopropylphenyl)-2-hydroxy-2-methylpropane-1-on,2-hydroxy-2-methyl-1-phenyl propane 1-on, and the like but the radicalgenerating agents are not limited thereto.

Examples of commercially-available items of the radical generating agentinclude Irgacure 184, 369, 651, 500, 819, 907, 784, 2959, CGI-1700,-1750, -1850, and CG24-61, Darocur 1116 and 1173, Lucirin TPO, LR8893,and LR8970 (all manufactured by BASF), Uvecryl P36 (manufactured byUCB), and the like but the commercially-available items are not limitedthereto.

Among the above, the component (B) of the photocurable composition fornanoimprint is suitably an acylphosphine oxide polymerization initiator.

Among the examples above, the acyl phosphine oxide polymerizationinitiator is an acyl phosphine oxide compound, such as 2,4,6-trimethylbenzoyl diphenyl phosphine oxide, bis(2,4,6-trimethyl benzoyl)phenylphosphine oxide, or bis(2,6-dimethoxy benzoyl)-2,4,4-trimethyl pentylphosphine oxide.

The compounding ratio of the component (B) which is aphotopolymerization initiator in the photocurable composition fornanoimprint is suitably 0.01% by weight or more and 10% by weight orless and more suitably 0.1% by weight or more and 7% by weight or lessbased on the total amount of the component (A) which is a polymerizablecompound.

By setting the compounding ratio of the component (B) to 0.01% by weightor more based on the total amount of the polymerizable compound, thecuring rate of a composition increases and the reaction efficiency canbe improved. By setting the compounding ratio of the component (B) to10% by weight or less based on the total amount of the polymerizablecompound, the photocured film to be obtained is a photocured film havinga certain degree of mechanical strength.

Other Additive Components (C)

The photocurable composition for nanoimprint of this embodiment maycontain further additive components (C) in addition to the component (A)and the component (B) described above according to various purposesinsofar as the effects of the present invention are not impaired.Examples of such additive components (C) include a sensitizer, ahydrogen donor, an internal mold release agent, a surfactant, anantioxidant, a solvent, a polymer component, and a polymerizationinitiator which is not the component (B), and the like.

The sensitizer is a compound to be added as appropriate for the purposeof promoting the polymerization reaction and improving the reactionconversion rate. As the sensitizer, a sensitizing dye and the like arementioned, for example.

The sensitizing dye is a compound which is excited by absorbing light ofa specific wavelength and interacts with the photopolymerizationinitiator which is the component (B). The interaction described hereinis energy transfer, electron transfer, and the like from the sensitizingdye in the excited state to the photopolymerization initiator which isthe component (B).

Specific examples of the sensitizing dye include an anthracenederivative, an anthraquinone derivative, a pyrene derivative, a perylenederivative, a carbazole derivative, a benzophenone derivative, athioxanthone derivative, a xanthone derivative, a coumarin derivative, aphenothiazine derivative, a camphorquinone derivative, an acridine dye,a thiopyrylium salt dye, a merocyanine dye, a quinoline dye, a styrylquinoline dye, a ketocoumarin dye, a thioxanthene dye, a xanthene dye,an oxonol dye, a cyanine dye, a rhodamine dye, a pyrylium salt dye, andthe like but the sensitizing dye is not limited thereto.

The sensitizers may be used alone or as a mixture of two or more kindsthereof.

The hydrogen donor is a compound which reacts with an initiation radicalgenerated from the photopolymerization initiator which is the component(B) or a radical at the polymerization growth terminal to generate aradical having higher reactivity. It is suitable to add the hydrogendonor when the photopolymerization initiator which is the component (B)is a photoradical generating agent.

Specific examples of such a hydrogen donor include amine compounds, suchas n-butylamine, di-n-butylamine, tri-n-butyl phosphine, allylthio urea,s-benzyl isothiuronium-p-toluene sulfinate, triethyl amine, diethylamino ethyl methacrylate, triethylene tetramine, 4,4′-bis(dialkylamino)benzophenone, N,N-dimethylamino benzoic acid ethyl ester,N,N-dimethylamino benzoic acid isoamyl ester, pentyl-4-dimethylaminobenzoate, triethanol amine, and N-phenylglycine, mercapto compounds,such as 2-mercapto-N-phenyl benzimidazole and mercaptopropionic acidester, and the like but the hydrogen donor is not limited thereto.

The hydrogen donors may be used alone or as a mixture of two or morekinds thereof.

The hydrogen donor may have a function as a sensitizer.

When the photocurable composition for nanoimprint of this embodimentcontains the sensitizer or the hydrogen donor as the additive component(C), the content of each of the sensitizer and the hydrogen donor issuitably 0.1% by weight or more and 20% by weight or less, more suitably0.1% by weight or more and 5.0% by weight or less, and still moresuitably 0.2% by weight or more and 2.0% by weight or less based on thetotal amount of the component (A) which is the polymerizable compound.When the sensitizer is contained in a proportion of 0.1% by weight ormore based on the total amount of the component (A), the polymerizationpromotion effect can be more effectively demonstrated. By setting thecontent of the sensitizer or the hydrogen donor to 5.0% by weight orless, the molecular weight of a high molecular weight compoundconfiguring a photocured film to be produced becomes sufficiently highand also poor dissolution in the photocurable composition fornanoimprint or degradation of the storage stability of the photocurablecomposition for nanoimprint can be suppressed.

For the purpose of reducing the interface bonding force between a moldand a resist, i.e., a reduction in mold releasing force in a moldrelease step, an internal mold release agent can be added to thephotocurable composition for nanoimprint. In this specification, theinternal type means that the mold release agent is added to a curablecomposition in advance before an arrangement step of the photocurablecomposition for nanoimprint.

As the internal mold release agent, surfactants, such as a siliconebased surfactant, a fluorine based surfactant, and a hydrocarbon basedsurfactant, and the like can be used. In this embodiment, the internalmold release agent does not have polymerizability.

The fluorine based surfactant includes polyalkylene oxide (polyethyleneoxide, polypropylene oxide, and the like) adducts of alcohols having aperfluoro alkyl group), polyalkylene oxides (polyethylene oxide,polypropylene oxide, and the like) adducts of perfluoropolyether, andthe like. The fluorine based surfactant may have a hydroxyl group, analkoxy group, an alkyl group, an amino group, a thiol group, and thelike in a part of the molecular structure (for example, terminal group).

As the fluorine based surfactant, commercially-available items may beused. Examples of the commercially-available items include, for example,Megafac F-444, TF-2066, TF-2067, and TF-2068 (all manufactured by DIC),Fluorad FC-430 and FC-431 (all manufactured by Sumitomo 3M Limited),Surflon S-382 (manufactured by AGC), EFTOP EF-122A, 122B, 122C, EF-121,EF-126, EF-127, and MF-100 (all manufactured by Tokem Products Co.,Ltd.), PF-636, PF-6320, PF-656, and PF-6520 (all manufactured by OMNOVASolutions), Unidyne DS-401, DS-403, and DS-451 (all manufactured byDaikin Industries), Ftergent 250, 251, 222F, and 208G (all manufacturedby NEOS Co. Ltd.), and the like.

The internal mold release agent may be a hydrocarbon based surfactant.

The hydrocarbon based surfactant includes alkylalcohol polyalkyleneoxide adducts obtained by adding alkylene oxide having 2 to 4 carbonatoms to alkyl alcohols having 1 to 50 carbon atoms and the like.

Examples of the alkylalcohol polyalkylene oxide adducts include a methylalcohol ethylene oxide adduct, a decyl alcohol ethylene oxide adduct, alauryl alcohol ethylene oxide adduct, a cetyl alcohol ethylene oxideadduct, a stearyl alcohol ethylene oxide adduct, a stearyl alcoholethylene oxide/propylene oxide adduct, and the like. The terminal groupof the alkylalcohol polyalkylene oxide adduct is not limited to ahydroxyl group which can be produced by simply adding polyalkylene oxideto alkyl alcohol. The hydroxyl group may be converted to othersubstituents, e.g., polar functional groups, such as a carboxyl group,an amino group, a pyridyl group, a thiol group, and a silanol group, andhydrophobic functional groups, such as an alkyl group and an alkoxygroup.

As the alkylalcohol polyalkylene oxide adduct, commercially-availableitems may be used. Examples of the commercially-available items includefor example, polyoxy ethylene methyl ether (methyl alcohol ethyleneoxide adduct) (BLAUNON MP-400, MP-550, and MP-1000) manufactured by AOKIOIL INDUSTRIAL Co., LTD., polyoxy ethylene decyl ether (decyl alcoholethylene oxide adduct) (FINESURF D-1303, D-1305, D-1307, and D-1310)manufactured by AOKI OIL INDUSTRIAL Co., LTD., polyoxy ethylene laurylether (lauryl alcohol ethylene oxide adduct) (BLAUNON EL-1505)manufactured by AOKI OIL INDUSTRIAL Co., LTD., polyoxy ethylenecetylether (cetyl alcohol ethylene oxide adduct) (BLAUNON CH-305 andCH-310) manufactured by AOKI OIL INDUSTRIAL Co., LTD., polyoxy ethylenestearyl ether (stearyl alcohol ethylene oxide adduct) (BLAUNON SR-705,SR-707, SR-715, SR-720, SR-730, and SR-750) manufactured by AOKI OILINDUSTRIAL Co., LTD., random polymerization type polyoxy ethylenepolyoxypropylene stearyl ether (BLAUNON SA-50/50 1000R and SA-30/702000R) manufactured by AOKI OIL INDUSTRIAL Co., LTD., polyoxy ethylenemethyl ether (Pluriol A760E) manufactured by BASF, polyoxyethylene alkylether manufactured by Kao Corporation (EMULGEN series), and the like.

Among the hydrocarbon based surfactants, the internal mold release agentis suitably an alkylalcohol polyalkylene oxide adduct and more suitablya long chain alkylalcohol polyalkylene oxide adduct.

The internal mold release agents may be used alone or as a mixture oftwo or more kinds thereof.

When the photocurable composition for nanoimprint of this embodimentcontains the internal mold release agent as the additive component (C),the content of the internal mold release agent is 0.001% by weight ormore and 10% by weight or less based on the total amount of thecomponent (A) which is the polymerizable compound. The content issuitably 0.01% by weight or more and 7% by weight or less and moresuitably 0.05% by weight or more and 5% by weight or less.

By analyzing the photocurable composition for nanoimprint of thisembodiment and/or a photocured film obtained by curing the same byinfrared spectroscopy, ultraviolet-visible spectroscopy, Pyrolysis-GasChromatography/Mass spectrometry, or the like, the proportions of thecomponent (A) and the component (B) can be determined, and consequentlythe proportions of the component (A) and the component (B) in thephotocurable composition for imprint can be determined. Also when theadditive component (C) is contained, the proportions of the component(A), the component (B), and the additive component (C) in thephotocurable composition for imprint can be similarly determined.

Glass Transition Temperature of Photocurable Composition for Imprint

The glass transition temperature of a photocured substance of thephotocurable composition for imprint of this embodiment is suitably 90°C. or more and more suitably 120° C. or more. It is considered that, bysetting the glass transition temperature to 90° C. or more, thermalexpansion and thermal distortion in dry etching are hard to occur.

As a method for measuring the glass transition temperature of thephotocured substance, the glass transition temperature can be measuredusing differential scanning calorimeter (DSC) or a dynamicviscoelasticity device.

For example, when the glass transition temperature is measured usingDSC, the extrapolation glass transition initiating temperature (Tig) isdetermined from the intersection of the straight line obtained byextending the baseline (DSC curve portion in a temperature region wheretransition and a reaction does not occur in a test piece) on the lowtemperature side of the DSC curve of the photocured substance to thehigh temperature side and the tangent drawn in such a manner that thegradient of the curve of a step-like change portion of the glasstransition reaches the maximum, and then the extrapolation glasstransition start temperature (Tig) can be determined as the glasstransition temperature. As a main device, STA-6000 (manufactured byPerkin Eimer) and the like are mentioned.

On the other hand, when the transition temperature is measured using adynamic viscoelasticity device, the temperature at which the losstangent (tan δ) of the photocured substance reaches the maximum isdefined as the glass transition temperature. As a main device capable ofmeasuring the dynamic viscoelasticity, MCR301 (manufactured by AntonPaar) and the like are mentioned.

In the present invention, it may be able to be confirmed that the glasstransition temperature is 90° C. or more by any one of the measuringmethods described above. A photocurable composition having a glasstransition temperature of 90° C. or more in the measurement of the losstangent using a dynamic viscoelasticity device is suitable. The dynamicviscoelasticity device can consistently perform the production of thephotocured substance and the measurement of the glass transitiontemperature and further the measurement of the coefficient of thermalexpansion described later.

Depending on the composition of the photocurable composition, due to thefact that a photopolymerization initiator having high absorption in theexposure wavelength (for example, around 365 nm) to be used in thedynamic viscoelasticity device is contained, the transmittance to a 0.1μm thick photocured film decreases, so that the glass transitiontemperature cannot be measured with good accuracy in some cases.Specifically, the measurement becomes difficult when the transmittanceis 30% or less.

In this case, it can be confirmed by the following method that thephotocurable composition for imprint has a glass transition temperatureof 90° C. or more.

3 parts by weight of Lucirin TPO which is a photopolymerizationinitiator (B) having low influence on a reduction in transmittance basedon 100 parts by weight of the photopolymerizable compound (A) to be usedis compounded to produce a photocurable composition, and then the losstangent tan δ of a photocured film is measured while increasing thetemperature. Then, due to the fact that the temperature at which the tanδ reaches the maximum is 90° C. or more, it can be specified that theglass transition temperature of the photocurable composition is 90° C.or more.

The composition of the photopolymerizable compound (A) is the mainfactor of determining the glass transition temperature. The influence ofthe photopolymerization initiator of a small content on the glasstransition temperature of the photocurable composition (B) is low.Therefore, it can be specified by carrying out the measuring methoddescribed above that the glass transition temperature of thephotocurable composition is 90° C. or more.

Temperature in Compounding Photocurable Composition for Imprint

When preparing the photocurable composition for imprint of thisembodiment, at least the component (A) and the component (B) are mixedand dissolved under predetermined temperature conditions. Specifically,the mixing and the dissolution are carried out in the range of 0° C. ormore and 100° C. or less. The same applies to the case where theadditive component (C) is contained.

Viscosity of Photocurable Composition for Imprint

The viscosity at 23° C. of a mixture of the components except a solventof the photocurable composition for imprint of this embodiment issuitably 1 mPa*s or more and 100 mPa*s or less, more suitably 3 mPa*s ormore and 50 mPa*s or less, and still more suitably 5 mPa*s or more and12 mPa*s or less.

By setting the viscosity of the photocurable composition for imprint to100 mPa*s or less, when the photocurable composition for imprint isbrought into contact with a mold, the time required for the compositionto fill into concave portions of a fine pattern on the mold is notprolonged. More specifically, the optical imprint method can be carriedout with high productivity. Moreover, pattern defects due to poorfilling are hard to occur.

By setting the viscosity to 1 mPa*s or more, when the photocurablecomposition for imprint is applied onto a substrate, applicationunevenness is hard to occur and, when the photocurable composition forimprint is brought into contact with a mold, the photocurablecomposition for imprint is difficult to flow out of end portions of themold.

Surface Tension of Photocurable Composition for Imprint

With respect to the surface tension of the photocurable composition forimprint of this embodiment, the surface tension at 23° C. of the mixtureof the components except a solvent is suitably 5 mN/m or more and 70mN/m or less, more suitably 7 mN/m or more and 35 mN/m or less, andstill more suitably 10 mN/m or more and 32 mN/m or less. Herein, bysetting the surface tension to 5 mN/m or more, when the photocurablecomposition for imprint is brought into contact with a mold, the timerequired for the composition to fill into concave portions of a finepattern on the mold is not prolonged.

By setting the surface tension to 70 mN/m or less, a photocured filmobtained by curing the photocurable composition for imprint is aphotocured film having surface smoothness.

Impurities Mixed in Photocurable Composition for Imprint

It is suitable for the photocurable composition for imprint of thisembodiment not to contain impurities as much as possible. The impuritiesdescribed herein mean substances other than the component (A), thecomponent (B), and the additive component (C) described above.

Therefore, the photocurable composition for imprint is suitably oneobtained passing through a purification step. As such a purificationstep, filtration using a filter or the like are suitable.

Specifically, when performing the filtration using a filter, it issuitable that the component (A), the component (B), and the additivecomponent to be added as necessary described above are mixed, and thenthe mixture is filtered with a filter having a pore size of 0.001 μm ormore and 5.0 μm or less. When performing the filtration using a filter,it is more suitable to perform the filtration in many stages or torepeat the filtration many times. The filtered liquid may be filteredagain. A plurality of filters having different pore sizes may be used.As the filter for use in the filtration, filters formed of polyethyleneresin, polypropylene resin, fluororesin, nylon resin, and the like canbe used but the filter is not particularly limited thereto.

By passing through such a purification step, impurities, such asparticles, mixed in the photocurable composition for imprint, can beremoved. Thus, pattern defects caused by irregularities accidentallyformed in a photocured film, which is obtained after curing thephotocurable composition for imprint, due to the impurities, such asparticles, can be prevented.

When the photocurable composition for imprint of this embodiment is usedfor manufacturing a semiconductor integrated circuit, it is suitable toavoid the mixing of impurities (metal impurities) containing metal atomsinto the photocurable composition for imprint as much as possible inorder not to inhibit an operation of a product. In such a case, theconcentration of the metal impurities contained in the photocurablecomposition for imprint is adjusted to suitably 10 ppm or less and moresuitably 100 ppb or less.

As described above, the present invention can take various aspects butsuitably takes an aspect containing at least either the following item(A) or (B):

(A) The polymerizable compound (A) at least contains 40% by weight ormore of a multifunctional (meth)acrylic monomer and the glass transitiontemperature of a photocured substance of a photocurable composition is120° C. or more; or(B) The multifunctional acrylic monomer contained in the polymerizablecompound (A) is any one of m-xylylene diacrylate, phenyl ethylene glycoldiacrylate, and 2-phenyl-1,3-propanediol diacrylate.

Method for Producing Film Having Pattern Shape

Next, a method for producing a film having a pattern shape of thisembodiment is described. FIGS. 1A to 1G are schematic cross sectionalviews illustrating an example of the method for producing a film havinga pattern shape of this embodiment.

The method for producing a film having a pattern shape of thisembodiment has:

[1] an arrangement step of arranging the photocurable composition forimprint of the embodiment described above on a substrate;[2] a mold contact step of bringing the photocurable composition forimprint into contact with a mold;[3] an alignment step of aligning the positions of the mold and asubstrate to be processed;[4] a light irradiation step of irradiating the photocurable compositionfor imprint with light; and[5] a releasing step of releasing the photocured film obtained by thestep [4] and the mold from each other.

The method for producing a photocured film having a pattern shape ofthis embodiment is a method for producing a film utilizing the opticalimprint method.

The photocured film obtained by the method for producing a photocuredfilm having a pattern shape of this embodiment is suitably a film havinga pattern of a size 1 nm or more and 10 mm or less and more suitably afilm having a pattern of a size of 10 nm or more and 100 μm or less. Ingeneral, a pattern formation technique of producing a film having apattern (irregular structure) of a nano size (1 nm or more 100 nm orless) utilizing light is referred to as an optical nanoimprint method.The method for producing a photocured film having a pattern shape ofthis embodiment employs the optical nanoimprint method.

Hereinafter, each step is described.

[Arrangement Step [1]]

In this step (arrangement step), a photocurable composition for imprint101 of this embodiment described above is arranged (applied) on asubstrate 102 to form a coating film as illustrated in FIG. 1A.

The substrate 102 which is a target on which the photocurablecomposition for imprint 101 is to be arranged is a substrate to beprocessed and a silicon wafer is usually used.

In this embodiment, however, the substrate 102 is not limited to thesilicon wafer and may be arbitrarily selected from those known assubstrates for semiconductor devices, such as aluminum, atitanium-tungsten alloy, an aluminum-silicon alloy, analuminum-copper-silicon alloy, silicon oxide, silicon nitride, and thelike for use. For the substrate 102 to be used (substrate to beprocessed), a substrate whose adhesiveness with the photocurablecomposition for imprint is improved by surface treatment, such as silanecoupling treatment, silazane treatment, and film formation of an organicthin film.

In this embodiment, as a method for arranging the photocurablecomposition for imprint on the substrate to be processed, for example,an ink jet method, a dip coating method, an air knife coating method, acurtain coating method, a wire bar coating method, a gravure coatingmethod, an extrusion coating method, a spin coating method, a slit scanmethod, and the like can be used. In the optical imprint method, the inkjet method is particularly suitable. The film thickness of a layer towhich a shape is to be transferred (coating film) varies depending onthe intended use and is 0.01 μm or more and 100.0 μm or less, forexample.

[Mold Contact Step [2]]

Next, as illustrated in FIGS. 1B(b-1) and 1B(b-2), a mold 104 having anoriginal pattern for transferring a pattern shape is brought intocontact with the coating film containing the photocurable compositionfor imprint 101 formed in the previous step (arrangement step). Bybringing the mold 104 into contact with the photocurable composition 101for imprint (layer to which a shape is to be transferred) in this step(FIG. 1B(b-1)), the coating film (partially) containing the photocurablecomposition for imprint 101 is filled into concave portions of a finepattern on the surface of the mold 104, so that a coating film 106filled into the fine pattern of the mold is obtained (FIG. 1B(b-2)).

The mold 104 is required to contain a light-transmitting material inconsideration of the following step (light irradiation step). Theconstituent material of the mold 104 is specifically suitably a lighttransparent resin, such as glass, quartz, PMMA, or polycarbonate resin,a flexible film, such as a transparent metal vapor deposition film orpolydimethyl siloxane, a photocured film, a metal film, or the like.However, when the light transparent resin is used as the constituentmaterial of the mold 104, it is necessary to select a resin which doesnot dissolve in the components contained in the photocurable compositionfor imprint 101. Quartz is particularly suitable because the thermalexpansion coefficient is low and pattern distortion is small.

The fine pattern on the surface of the mold 104 suitably has a patternheight of 4 nm or more and 200 nm or less and an aspect ratio of 1 ormore and 10 or less.

In order to increase the releasability of the photocurable compositionfor imprint 101 and the surface of the mold 104, the mold 104 may besurface treated before this step which is the mold contact step of thephotocurable composition for imprint and the mold. As the surfacetreatment method, a method including applying a mold release agent tothe surface of the mold to form a mold release agent layer is mentioned.Herein, examples of the mold release agent to be applied to the surfaceof the mold include a silicone mold release agent, a fluorine moldrelease agent, a hydrocarbon mold release agent, a polyethylene moldrelease agent, a polypropylene mold release agent, a paraffin moldrelease agent, a montan mold release agent, a carnauba mold releaseagent, and the like. For example, a commercially-available coating typemold release agent, such as Optool DSX manufactured by DaikinIndustries, LTD. can also be suitably used. The mold release agents maybe used alone or in combination of two or more kinds thereof. Among theabove, the fluorine mold release agent and the hydrocarbon mold releaseagent are particularly suitable.

In this step (mold contact step), when the mold 104 and the photocurablecomposition for imprint 101 are brought into contact with each other asillustrated in FIG. 1B(b-1), the pressure to be applied to thephotocurable composition for imprint 101 is not particularly limited andis usually 0 MPa or more and 100 MPa or less. In particular, thepressure is suitably 0 MPa or more and 50 MPa or less, more suitably 0MPa or more and 30 MPa or less, and still more suitably 0 MPa or moreand 20 MPa or less.

The period of time while the mold 104 is brought into contact with thephotocurable composition for imprint 101 in this step is notparticularly limited and is usually 0.1 second or more and 600 secondsor less, suitably 0.1 second or more and 300 seconds or less, still moresuitably 0.1 second or more and 180 seconds or less, and particularlysuitably 0.1 second or more and 120 seconds or less.

This step can also be performed under any condition of under an airatmosphere, under reduced pressure atmosphere, and under an inactive gasatmosphere and the reduced pressure atmosphere or the inactive gasatmosphere is suitable because influence of oxygen or moisture on thecuring reaction can be prevented. Specific examples of the inactive gasusable when performing this step under the inactive gas atmosphereinclude nitrogen, carbon dioxide, helium, argon, various kinds offluorocarbon gas, and the like or a mixed gas thereof. When performingthis step under a specific gas atmosphere including the air atmosphere,a suitable pressure is 0.0001 atm or more and 10 atm or less.

The mold contact step may be performed under an atmosphere containingcondensable gas (hereinafter referred to as a condensable gasatmosphere). The condensable gas in this specification refers to gaswhich is condensed and liquefied by the capillary pressure generatedwhen the gas in the atmosphere is filled into the concave portions ofthe fine pattern formed on the mold 104 and a gap between the mold andthe substrate together with the coating film (partially) 106. Thecondensable gas is present in the form of gas in the atmosphere beforethe photocurable composition 101 (layer to which a shape is to betransferred) and the mold 104 are brought into contact with each otherin the mold contact step (FIG. 1B(b-1)).

When the mold contact step is performed under the condensable gasatmosphere, air bubbles disappear due to the liquefaction of the gasfilled into the concave portions of the fine pattern, and thus thefilling properties are excellent. The condensable gas may dissolve inthe photocurable composition 101.

The boiling point of the condensable gas is not particularly limitedinsofar as the boiling point is equal to or less than the atmospherictemperature of the mold contact step and is suitably −10° C. to 23° C.and more suitably 10° C. to 23° C. When the boiling point is in thisrange, the filling properties are more excellent.

The vapor pressure of the condensable gas at the atmospheric temperaturein the mold contact step is not particularly limited insofar as thevapor pressure is equal to or less than the mold pressure when impressedin the mold contact step and is suitably 0.1 to 0.4 MPa. When the vaporpressure is in this range, the filling properties are more excellent.When the vapor pressure at the atmospheric temperature is larger than0.4 MPa, there is a tendency that the effect that air bubbles disappearcannot be sufficiently obtained. On the other hand, when the vaporpressure at the atmospheric temperature is smaller than 0.1 MPa, thepressure needs to be reduced, so that there is a tendency for a deviceto be complicated.

The atmospheric temperature of the mold contact step is not particularlylimited and is suitably 20° C. to 25° C.

Specific examples of the condensable gas include chlorofluocarbon, suchas: chlorofluorocarbon (CFC), such as trichlorofluoro methane,hydrofluorocarbon (HFC), such as fluorocarbon (FC),hydrochlorofluorocarbon (HCFC), and 1,1,1,3,3-pentafluoro propane(CHF₂CH₂CF₃,HFC-245fa, PFP), and hydrofluoro ether (HFE), such aspentafluoroethyl methyl ether (CF₃CF₂OCH₃, HFE-245mc).

Among the above, from the viewpoint that the filling properties at anatmospheric temperature of 20° C. to 25° C. in the mold contact step areexcellent, 1,1,1,3,3-pentafluoro propane (Vapor pressure at 23° C. of0.14 MPa, Boiling point of 15° C.), trichlorofluoro methane (Vaporpressure at 23° C. of 0.1056 MPa, Boiling point of 24° C.), andpentafluoroethyl methyl ether are suitable. From the viewpoint that thesafety is excellent, 1,1,1,3,3-pentafluoro propane is particularlysuitable.

The condensable gas may be used alone or as a mixture of two or morekinds thereof. The condensable gas may be mixed with non-condensablegas, such as air, nitrogen, carbon dioxide, helium, and argon for use.The non-condensable gas to be mixed with the condensable gas is suitablyhelium from the viewpoint of the filling properties. Helium can permeatethe mold 104. Therefore, when the gas (condensable gas and helium) inthe atmosphere is filled into the concave portions of the fine patternformed on the mold 104 together with the coating film (partially) 106 inthe mold contact step, the condensable gas is liquefied and also heliumpermeates the mold.

[Alignment Step [3]]

Next, as illustrated in FIG. 1C, the positions of the mold and/or thesubstrate to be processed are adjusted in such a manner that a mold sidealigning mark 105 and an aligning mark 103 of the substrate to beprocessed are in agreement with each other.

[Light Irradiation Step [4]]

Next, a contact portion with the mold of the photocurable compositionfor imprint, in detail the coating film 106 filled into the fine patternof the mold, is irradiated with light through the mold 104 in the statewhere the positions are aligned in the step [3] as illustrated in FIG.1D (FIG. 1D(d-1)). Thus, the coating film 106 filled into the finepattern of the mold 104 is cured by the emitted light to be a photocuredfilm 108 (FIG. 1D(d-2)).

Herein, the light irradiating the photocurable composition for imprint101 configuring the coating film 106 filled into the fine pattern of themold is selected according to the sensitivity wavelength of thephotocurable composition for imprint 101. Specifically, it is suitableto select ultraviolet light of a wavelength of 150 nm or more and 400 nmor less, X-rays, electron beams, or the like as appropriate for use.

Among the above, the light (irradiation light 107) irradiating thephotocurable composition for imprint 101 is particularly suitablyultraviolet light. This is because those commercially available as acuring assistant (photopolymerization initiator) are compounds havingsensitivity in ultraviolet light in many cases. Herein, examples of alight source emitting ultraviolet light include, for example, a highpressure mercury lamp, an ultrahigh pressure mercury lamp, a lowpressure mercury lamp, a Deep-UV lamp, a carbon arc light, a chemicallamp, a metal halide lamp, a xenon lamp, a KrF excimer laser, an ArFexcimer laser, an F₂ excimer laser, and the like and the ultrahighpressure mercury lamp is particularly suitable. The number of the lightsources to be used may be one or two or more. When performing the lightirradiation, the light irradiation may be performed to the entiresurface of the coating film 106 or only to a partial region thereof.

The light irradiation may be intermittently performed to the entireregion on the substrate two or more times or may be continuouslyperformed to the entire region. Or, a partial region A may be irradiatedwith light in a first irradiation step, and then a region B differentfrom the region A may be irradiated with light in a second irradiationstep.

[Mold Release Step [5]]

Next, the photocured film 108 and the mold 104 are released from eachother. In this case, a photocured film 109 having a predeterminedpattern shape is formed on the substrate 102.

In this step (mold release step), the photocured film 108 and the mold104 are released from each other, and then the photocured film 109having a pattern shape serving as a reversal pattern of the fine patternformed on the mold 104 is obtained in the step [4] (light irradiationstep) as illustrated in FIG. 1E.

By a series of steps (manufacturing step) having the step [1] to step[5] above, the photocured film having a desired irregular pattern shape(pattern shape following the irregular shape of the mold 104) at adesired position can be obtained. The obtained photocured film can alsobe utilized as optical members (including the case where the photocuredfilm is used as one member of an optical member), such as a Fresnel lensand a diffraction grating, for example. In such a case, the photocuredfilm can be used as an optical member at least having the substrate 102and the photocured film 109 having a pattern shape arranged on thesubstrate 102.

According to the method for producing a film having a pattern shape ofthis embodiment, a repetition unit (shot) including the step [1] to thestep [5] can be repeatedly performed two or more times on the samesubstrate to be processed. By repeating the repetition unit (shot)including the process [1] to the process [5] two or more times, aphotocured film having a plurality of desired irregular pattern shapes(pattern shape following the irregular shape of the mold 104) at desiredpositions of the substrate to be processed can be obtained.

[Remaining Film Removal Step [6] of Removing a Part of Photocured Film]

The photocured film obtained by the mold release process which is theprocess [5] has a specific pattern shape but the photocured films maypartially remain also in regions other than the region where the patternshape is formed (in the following description, such a part of thephotocured film is sometimes referred to as a remaining film). In such acase, the obtained photocured film (remaining film) in the region to beremoved of the photocured film having the pattern shape is removed,whereby a photocured film pattern 110 having a desired irregular patternshape (pattern shape following the irregular shape of the mold 104) canbe obtained as illustrated in FIG. 1F.

Herein, as a method for removing the remaining film, a method removingthe photocured film (remaining film) serving as the concave portions ofthe photocured film 109 by a method, such as etching, for example, toexpose the surface of the substrate 102 in the concave portions of thepattern of the photocured film 109 is mentioned.

When the photocured film in the concave portions of the photocured film109 is removed by etching, a specific method therefor is notparticularly limited and known methods, e.g., dry etching, can be used.For the dry etching, a known dry etching device can be used. A sauce gasin the dry etching is selected as appropriate according to the elementcomposition of the photocured film which is to be etched and halogengas, such as CF₄, C₂F₆, C₃F₈, CCl₂F₂, CCl₄, CBrF₃, BCl₃, PCl₃, SF₆, andCl₂, gas containing oxygen atoms, such as O₂, CO, and CO₂, inactive gas,such as He, N₂, and Ar, and gas, such as H₂ and NH₃, and the like can beused. The gas can also be mixed for use.

By the manufacturing step including the step [1] to the step [6] above,the photocured film pattern 110 having a desired irregular pattern shape(pattern shape following the irregular shape of the mold 104) at desiredpositions can be obtained and articles having the photocured filmpattern can be obtained. When the substrate 102 is processed using theobtained photocured film pattern 110, a substrate processing step (Step[7]) described later is performed.

On the other hand, the obtained photocured film pattern 110 can beutilized as optical members (including the case where the photocuredfilm pattern 110 is used as one member of an optical member), such as adiffraction grating and a polarizing plate, and then an opticalcomponent can also be obtained. In such a case, an optical component atleast having the substrate 102 and the photocured film pattern 110arranged on the substrate 102 can be obtained.

[Substrate Processing Step [7]]

The photocured film pattern 110 having an irregular pattern shape whichis obtained by the method for producing a photocured film having apattern shape of this embodiment can also be used as, for example, afilm for interlayer insulation film contained in electronic componentstypified by semiconductor devices, such as LSI, System LSI, DRAM, SDRAM,RDRAM, and D-RDRAM, and can also be used as a resist film inmanufacturing semiconductor devices.

When the photocured film pattern 110 is utilized as a resist film,etching or ion implantation is performed to a part of the substrateexposed in the etching step which is Step [6](region denoted by thereference numeral 111 in FIG. 1F). In this case, the photocured filmpattern 110 functions as an etching mask. In addition thereto, byconfiguring electronic components, a circuit structure 112 (FIG. 1G)based on the pattern shape of the photocured film pattern 110 can beformed on the substrate 102. Thus, a circuit board to be utilized insemiconductor devices and the like can be manufactured. By connectingthe circuit board and a circuit control mechanism of the circuit board,electronic devices, such as displays, cameras, and medical devices, canalso be configured.

Similarly, optical components can also be obtained by performing etchingor ion implantation utilizing the photocured film pattern 110 as aresist film.

When producing substrates with a circuit and electronic components, thephotocured film pattern 110 may be finally removed from the processedsubstrate but a configuration in which the photocured film pattern 110may be left as a member configuring an element may be acceptable.

Other Embodiments

The photocured film formed by the method is suitable for the use inwhich the photocured film is processed by a dry etching step. Morespecifically, the photocured film is useful as a photocured film for dryetching to be used for a dry etching process which is obtained by curingthe photocurable composition for imprint on a substrate.

By passing through the steps described above, a semiconductor substratepretreated by dry etching having a semiconductor substrate and thephotocured film for dry etching patterned on the semiconductor substratecan be provided.

EXAMPLES

Hereinafter, the present invention is described in detail with referenceto Examples but the technical scope of the present invention is notlimited to Examples described below. “Part(s)” used in the followingdescription is a unit based on weight (part by weight) unless otherwiseparticularly specified.

Reagents (polymerizable compounds, polymerization initiators) used inany one of Examples and Comparative Examples and contained inphotocurable compositions for imprint are mentioned below.

(A) Polymerizable Compound

<A1> Isobornyl acrylate (manufactured by Kyoeisha Chemical Co., Ltd.,Trade name: IB-XA)<A2> Benzyl acrylate (manufactured by Osaka Organic Chemical IndustryCo., Ltd., Trade name: V #160)<A3> Dicyclopentanyl acrylate (manufactured by Hitachi Chemical Co.,Ltd., Trade name: FA-513AS)<A4>2-naphthyl methyl acrylate (manufactured by NARD institute, Ltd.)<A5> Diphenyl methanol acrylate (manufactured by NARD institute, Ltd.)<A6>1,6-hexanediol diacrylate (manufactured by Osaka Organic ChemicalIndustry Co., Ltd., Trade name: V #230)<A7>1,10-decanediol diacrylate (manufactured by Osaka Organic ChemicalIndustry Co., Ltd., Trade name: V #230)<A8> Dimethylol tricyclodecane diacrylate (manufactured by KyoeishaChemical Co., Ltd., Trade name: DCP-A)<A9> Phenylethylene glycol diacrylate (manufactured by NARD institute,Ltd.)<A10> m-xylylene diacrylate (manufactured by NARD institute, Ltd.)<A11>2-phenyl-1,3-propane diol diacrylate (manufactured by NARDinstitute, Ltd.)

(B) Polymerization Initiator

<B1> Lucirin TPO (Manufactured by BASF Japan)

The compositions of photocurable compositions for imprint produced usingthe materials mentioned above are shown in Table 1 shown below. Afterthe preparation, filtration with a 0.2 μm filter containing ultrahighmolecular weight polyethylene was performed.

TABLE 1 Polymerization Polymerizable compound initiator [part by weight][part by weight] A1 A2 A3 A4 A5 A6 A7 A8 A9 A10 A11 B1 Example 1 60 — —— — — — — — 40 — 3 Example 2 50 — — — — — — — — 50 — 3 Example 3 75 — —— — — — — — 25 — 3 Example 4 — — 60 — — — — — — 40 — 3 Example 5 — — 50— — — — — — 50 — 3 Example 6 — — — 60 — — — — — 40 — 3 Example 7 — — — —75 25 — — — — — 3 Example 8 — — — — — — — — 100 — — 3 Example 9 — 50 — —— — — — — — 50 3 Example 10 — — — — — — — — — — 100 3 Comparative 100 —— — — — — — — — — 3 Example 1 Comparative — — 100 — — — — — — — — 3Example 2 Comparative — — — 100 — — — — — — — 3 Example 3 Comparative —— — — 100 — — — — — — 3 Example 4 Comparative — 75 — — — — — 25 — — — 3Example 5 Comparative — 60 — — — — — 40 — — — 3 Example 6 Comparative —50 — — — 50 — — — — — 3 Example 7 Comparative — 50 — — — — 50 — — — — 3Example 8

For the photocurable compositions for imprint shown in Table 1 above,the measurement of viscosity, glass transition temperature, and dryetching was performed using the following procedure, and then thecoefficient of thermal expansion, the Ohnishi parameter, and the etchingrate were calculated.

(1. Measurement of Viscosity of Photocurable Composition for Imprint)

The viscosity of the photocurable compositions for imprint at 23° C. wasmeasured using a cone-plate type rotation viscometer RE-85L(manufactured by Toki Sangyo Co., Ltd.).

(2. Production of Photocured Film for Measurement of Glass TransitionTemperature of Photocurable Composition for Imprint)

70 μl of a resist was added dropwise and filled into a 100 μm gapbetween a rotating rod having a bottom surface with a diameter ϕ of 8.0mm and a quartz stage using a rheometer MCR301 with a UV irradiationoption manufactured by Anton Paar. The normal reaction of the rotatingrod was set to zero N in such a manner that the gap followed curing andshrinkage of the photocurable composition.

Next, the rotational vibration cycle of the rotating rod was set to 5Hz, and 10 seconds after starting the rotation vibration, UV lightirradiation was started from the quartz stage side. The exposure timewas set to 600 seconds, the exposure wavelength was fixed to 365 nm, theilluminance was fixed to 1.0 mW/cm², and the temperature was fixed to23° C.

(3. Measurement of Glass Transition Temperature and Coefficient ofThermal Expansion of Photocurable Composition for Imprint)

In the state where the normal reaction of the rotating rod was set tozero N in such a manner that the gap between the rotating rod and thequartz stage followed thermal expansion and thermal shrinkage of thephotocurable composition, the photocured film produced in (2) wasmeasured for the loss tangent tan δ while increasing the temperaturefrom 23° C. to 200° C. The temperature increase rate was set to 4°C./min. The temperature at which the tan δ reached the maximum wasdefined as the glass transition temperature. Further, the coefficient ofthermal expansion of the photocured film was calculated by the followingexpression (3).

Film thickness (μm) of photocured film at 120° C./Film thickness (μm) ofphotocured film at 23° C.=Coefficient of thermal expansion (%)  (3)

Herein, the film thickness of the photocured film is a gap between therotating rod and the quartz stage.

(4. Calculation of Ohnishi Parameter of Photocurable Composition forImprint)

The Ohnishi parameter of the (A) component of the photocurablecompositions shown in the composition table shown in Table 1 wascalculated using the following expression (2).

OP=n ₁ OP ₁ +n ₂ OP ₂ + . . . +n _(n) OP _(n)  (2)

(5. Production of Photocured Film for Dry Etching of PhotocurableComposition for Imprint)

2 μL of the prepared photocurable composition for imprint was addeddropwise onto a silicon wafer on which a 60 nm thick adhesion promotionlayer was formed as an adhesion layer, a 1 mm thick quartz glass wascovered from the top, and then a region (25 mm×25 mm) was filled withthe photocurable composition for imprint.

Next, light emitted from a UV light source having an ultrahigh pressuremercury lamp from the top of the quartz glass was made to pass throughan interference filter described later, and then emitted to a coatingfilm for 200 seconds through the quartz glass. The interference filterused in the light irradiation was VPF-25C-10-15-31300 (manufactured bySIGMAKOKI Co., LTD.). The wavelength of the ultraviolet light which wasthe irradiation light was a single wavelength light of 313±5 nm and theilluminance was set to 1 mW/cm².

After the light irradiation, the quartz glass was peeled, and then aphotocured film of the photocurable composition for imprint having anaverage film thickness of 3.2 μm was obtained on the silicon wafer.

(6. Measurement of Etching Rate of Photocured Film for Dry Etching ofPhotocurable Composition for Imprint)

Dry etching was performed for 500 seconds to the photocured filmproduced in (5) using a high density plasma etching device NE-550manufactured by ULVAC and setting etching gas and the flow rate thereofto CF₄/CHF₃=50 sccm/50 sccm, and then the film thickness reduced by thedry etching was measured to calculate the dry etching rate (nm/s). Alower etching rate indicates that the dry etching resistance is higher.

The measurement results above are shown in Table 2 shown below. The dryetching rate ratio (DE rate ratio) was obtained by calculating therelative value, when the composition of Comparative Example 1 was set to1, in terms of percentage.

TABLE 2 Coefficient Multifunctional Glass transition of thermal DE ratemonomer ratio temperature expansion ratio Viscosity [part by weight] (°C.) [%] OP [%] [mP*s] Example 1 40 154 1 3.19 81 9.2 Example 2 50 168 33.19 81 9.7 Example 3 25 141 6 3.19 85 8.5 Example 4 40 131 3 3.07 7811.4 Example 5 50 143 7 3.09 78 11.7 Example 6 40 95 6 2.65 72 10.7Example 7 25 92 8 2.80 82 15.7 Example 8 100 >200 6 3.20 100 23.0Example 9 100 >101 — 2.92 85 6.1 Example 10 100 >200 — 3.18 90 36.6Comparative 0 132 18 3.18 100 7.5 Example 1 Comparative 0 109 13 3.00 8110.6 Example 2 Comparative 0 95 10 2.33 73 9.6 Example 3 Comparative 086 10 2.29 83 22.1 Example 4 Comparative 25 55 13 2.83 96 4.2 Example 5Comparative 40 75 15 2.89 91 6.6 Example 6 Comparative 50 65 19 3.38 1053.4 Example 7 Comparative 50 45 22 3.15 101 3.8 Example 8

It can be confirmed from the results shown in Table 2 that thephotocurable compositions for imprint of Examples have a small thermalexpansion.

Considering the fact that the coefficient of thermal expansion is lessthan 10% in Examples 1 to 8, Examples 1 to 8 are compositions in whichthe thermal expansion of the resist in the dry etching was small.Furthermore, considering the fact that the DE rate ratio is equal to orhigher than that of Comparative Example 1, Examples 1 to 8 arecompositions having excellent dry etching resistance. Since theviscosity is also 50 mPa*s or less, the filling properties are alsoexcellent. Considering the fact that Examples 9 and 10 have a DE rateratio smaller than that of Comparative Example 1 and having a viscosityof 50 mPa*s or less, it is considered that Examples 9 and 10 arecompositions having a small thermal expansion similarly to Examples 1 to8.

On the other hand, in Comparative Examples 1 to 3, the glass transitiontemperature is 90° C. or more but the coefficient of thermal expansionis 10% or more. This is considered to be because the proportion of themultifunctional monomer is less than 20% by weight, i.e., only themonofunctional acrylic monomer is contained, and therefore the crosslinkdensity of Comparative Examples 1 to 3 is lower than that of thecompositions containing 20% by weight or more of the multifunctionalacrylic monomer as in Examples 1 to 8. More specifically, it isconsidered that thermal distortion and thermal expansion are likely tooccur in dry etching.

Comparative Examples 5 to 8 are compositions containing 20% by weight ormore of the multifunctional monomer but the coefficient of thermalexpansion is 10% or more. This is considered to be because the glasstransition temperature is low, and therefore thermal distortion andthermal expansion are likely to occur in dry etching similarly toComparative Examples 1 to 4.

It can be confirmed that, due to the fact that the multifunctionalmonomer is not contained, the composition of Examples 1 to 8 arephotocurable compositions for imprint having small thermal expansion,excellent dry etching resistance, and also excellent filling properties.

INDUSTRIAL APPLICABILITY

As described above, the present invention can provide a photocurablecomposition for imprint having small thermal expansion in dry etchingand excellent filling properties in an optical imprint method. Moreover,the present invention can also provide a method for producing thephotocurable composition for imprint, a method for producing a film, amethod for producing an optical component, a method for producing acircuit board, and a method for producing an electronic component.

The present invention can provide a photocurable composition for imprinthaving small thermal expansion in dry etching and excellent fillingproperties in an optical imprint method. Moreover, the present inventioncan also provide a method for producing a film using the photocurablecomposition for imprint, a method for producing an optical componentusing the photocurable composition for imprint, a method for producing acircuit board using the photocurable composition for imprint, and amethod for producing an electronic component using the photocurablecomposition for imprint.

While the present invention has been described with reference toexemplary embodiments, it is to be understood that the invention is notlimited to the disclosed exemplary embodiments. The scope of thefollowing claims is to be accorded the broadest interpretation so as toencompass all such modifications and equivalent structures andfunctions.

1. A photocurable composition for a cured film which is obtained bycuring the photocurable composition applied on a substrate and used whenetching the substrate, the photocurable composition at least comprising:a polymerizable compound (A); and a photopolymerization initiator (B),wherein the polymerizable compound (A) contains 25% by weight or more ofa multifunctional (meth)acrylic monomer, wherein a glass transitiontemperature of a photocured substance of the photocurable composition is101° C. or more, wherein the polymerizable compound (A) is a mixture ofa monofunctional (meth)acrylic monomer and a multifunctional(meth)acrylic monomer, wherein an Ohnishi parameter of the polymerizablecompound (A) is 3.2 or less.
 2. The photocurable composition accordingto claim 1, wherein the polymerizable compound (A) contains 40% byweight or more of the multifunctional (meth)acrylic monomer.
 3. Thephotocurable composition according to claim 1, wherein a glasstransition temperature of a photocured substance of the photocurablecomposition is 131° C. or more.
 4. The photocurable compositionaccording to claim 1, wherein a viscosity of the photocurablecomposition is 5 mPa*s or more and 50 mPa*s or less.
 5. The photocurablecomposition according to claim 1, wherein a viscosity of thephotocurable composition is 3 mPa*s or more and 10.6 mPa*s or less. 6.The photocurable composition according to claim 1, wherein thephotocurable composition having a glass transition temperature of 101°C. or more is specified by measuring a loss tangent tan δ of a filmobtained by photocuring a photocurable composition containing 100 partsby weight of the polymerizable compound (A) and 3 parts by weight ofLucirin TPO as the photopolymerization initiator (B) while increasing atemperature to find out that a temperature at which the tan δ reaches amaximum is 101° C. or more.
 7. The photocurable composition according toclaim 1, wherein a multifunctional acrylic monomer contained in thepolymerizable compound (A) is any one of m-xylylene diacrylate, phenylethylene glycol diacrylate, and 2-phenyl-1,3-propanediol diacrylate. 8.A method for producing a film comprising: a step (1) of arranging thephotocurable composition according to claim 1 on a substrate; a step (2)of bringing the curable composition into contact with a mold; a step (3)of aligning the substrate and the mold; a step (4) of irradiating thecurable composition with light to form a photocured film; and a step (5)of releasing the cured film and the mold from each other.
 9. The methodfor producing a film according to claim 8, comprising performing thesteps (1) to (5) two or more times to different regions on thesubstrate.
 10. The method for producing a film according to claim 8,wherein a surface of the mold contains quartz.
 11. The method forproducing a film according to claim 8, wherein the step (2) is performedunder an atmosphere containing condensable gas.
 12. A method forproducing an optical component, comprising the step of obtaining a filmby the manufacturing method according to claim
 8. 13. A method forproducing an optical component, comprising: a step of obtaining a filmby the manufacturing method according to claim 8; and a step ofperforming etching or ion implantation to a substrate.
 14. A method forproducing a circuit board, comprising: a step of obtaining a film by themanufacturing method according to claim 8; and a step of performingetching or ion implantation to a substrate using the obtained film. 15.A method for producing an electronic component, comprising: a step ofobtaining a circuit board by the method for producing a circuit boardaccording to claim
 14. 16. The method for producing an electroniccomponent according to claim 15, wherein the electronic component is asemiconductor device.
 17. A photocured film for dry etching, which isused for dry etching, the photocured film being obtained by curing thephotocurable composition according to claim 1 on the substrate.
 18. Asemiconductor substrate pretreated by dry etching, comprising: asemiconductor substrate; and the photocured film for etching accordingto claim 17 patterned onto the semiconductor substrate.